1. Field of the Invention
The present invention relates to an improved apparatus useful in identifying the chemical nature or structure of substances, and, more particularly, an improved apparatus for pyrolyzing substances to generate volatile and breakdown components of such substances.
2. Description of the Prior Art
Numerous analytical techniques such as gas chromotography, mass spectroscopy, infared spectroscopy, etc. are available for analyzing chemical compounds and mixtures. However, many, complex chemical substances, particularly solids, cannot be analyzed effectively by such techniques because of the myriad of individual chemical compounds present in the substances or because the substance is a highly complex material, e.g. a polymer.
One area where analysis of complex chemical substances is extremely important involves petroleum exploration. It is common, during drilling an oil or gas well, to regularly chemically analyze formation samples taken from the well to determine the presence of commercial quantities of hydrocarbon material. Typically, such analyses have been carried out through laborious and time consuming chemical techniques which must be carried out in a well equipped laboratory precluding effective and rapid on-site analysis of the samples. Considering that the hydrocarbon content of source rock and reservoir rock formations is extremely critical in determining whether to continue drilling, or to institute production procedures from the well, rapid, on-site analysis of the source rock or reservoir rock is clearly desirable.
There are other instances in which the chemical makeup of a substance is difficult to ascertain with conventional analytial techniques. For example, in the case of polymeric materials, precise chemical structure is often times impossible to ascertain. Naturally occurring chemical substances, such as materials derived from plant sources, also present extremely complex mixtures of chemical compounds which are difficult to analyze using conventional techniques.
In all of the instances mentioned above, analysis would be greatly facilitated if the complex chemical substances could be "taken apart", either by evolving the more volatile components from the substances and/or by breaking down the non-volatile components into compounds which are more easily identified. To this end, pyrolytic analysis has proved to be a valuable tool in the analysis of complex chemical substances.
As is well known, in a typical pyrolysis technique, the substance to be analyzed is subjected to increasing temperature so as to accomplish a selective release of the volatile components from the substance generally followed by applying a temperature at which the non-volatile components are degraded or pyrolyzed into breakdown products which are more susceptible to analysis.
Unfortunately, the pyrolysis technique suffers from several disadvantages. For one, because the volatile components or breakdown components from the substance being analyzed are at elevated temperature, they are prone to reaction to form other products which will give misleading results as to the composition of the original substance. Since many apparatuses used for pyrolysis employ reactive materials, such as stainless steel and other metals, the volatile products and/or breakdown products can react or be adsorbed on these "chemically active" surfaces and either be converted into other products, react with other volatile or breakdown components to form new products or be held by the adsorbent surfaces and not reach the detector.